In the present study, rather than assessing MPS, our interest was primarily Alvocidib nmr focused on the extent with which 10 g of whey protein comprised of 5.25 EAAs would affect the activity of the Akt/mTOR pathway after resistance exercise when compared to carbohydrate alone and if this activity might also be systemically affected
by either insulin or IGF-1. The reason for our interest was an attempt to discern if the 5.25 g of EAAs contained within 10 g of whey protein, without carbohydrate, was adequate to activate the Akt/mTOR compared to carbohydrate in response to a single bout of resistance exercise. Our interest was heightened by a previous study in which albumin protein intake at 10 g (4.3 g EAAs) significantly increased MPS, and maximally MK-2206 molecular weight when 20 g (8.6 g EAAs) and 40 g (16.4 g EAAs) were ingested, yet none of the three concentrations had any affect on the activities of the
Akt/mTOR pathway intermediates S6K1 (Thr389), rps6 (Ser240/244), or eIF2Bε (Ser539) at 60 and 240 min post-exercise . Despite previous evidence indicating otherwise , we were curious to determine if 10 g of whey protein would produce increases in other key Akt/mTOR signalling intermediates following resistance exercise. It is evident that acute resistance exercise results in a significant increase in the rate of initiation of protein synthesis compared with resting muscle . It is suggested that signal transduction pathways control the rate of initiation of MPS, and appear to be the key factors in the hypertrophic process [34, 35]. Of particular importance is the complex myriad of signaling proteins, with Akt suggested to be a key selleck compound regulator. Maximal activation of Akt occurs through phosphorylation of Ser473 and it appears that Akt may have a relatively short period of activation after an acute bout of resistance exercise . Research into the regulation Sunitinib of Akt signalling by exercise has produced conflicting
results. A series of studies have demonstrated that contractile activity either positively or negatively regulates Akt activity [15, 37–39], while others failed to find any change [40–42]. In the current study, we found that resistance exercise and nutrient ingestion failed to induce a significant change in the phosphorylation of Akt. Stimuli of the Akt pathway includes hormones and muscle contraction. Insulin  and IGF-I  bind to their respective membrane-bound receptors and subsequently activate phosphatidylinositol-3 kinase (PI-3K), an upstream activator for Akt phosphorylation. Quantification of circulating IGF-I levels has yielded inconsistent results, with levels being reported to decline , increase , or remain unchanged  after the onset of exercise. Furthermore, circulating IGF-1 has been shown to have no direct effect on muscle hypertrophy .